HDLC. High-Level Data Link Control (HDLC) is a bit-oriented code-transparent synchronous data link layer protocol developed by the International Organization for Standardization (ISO).
The original ISO standards for HDLC are: ISO 3309 – Frame StructureISO 4335 – Elements of ProcedureISO 6159 – Unbalanced Classes of ProcedureISO 6256 – Balanced Classes of Procedure. What is HDLC. What is HDLC. Main » TERM » H » Short for High-level Data Link Control, a transmission protocol used at the data link layer (layer 2) of the OSI seven layer model for data communications.
The HDLC protocol embeds information in a data frame that allows devices to control data flow and correct errors. HDLC is an ISOstandard developed from the Synchronous Data Link Control (SDLC) standard proposed by IBM in the 1970's. Abstract Syntax Notation One. Abstract Syntax Notation One (ASN.1) is a standard and notation that describes rules and structures for representing, encoding, transmitting, and decoding data in telecommunications and computer networking.
The formal rules enable representation of objects that are independent of machine-specific encoding techniques. Formal notation makes it possible to automate the task of validating whether a specific instance of data representation abides by the specifications. In other words, software tools can be used for the validation.[1] ASN.1 is a joint standard of the International Organization for Standardization (ISO), International Electrotechnical Commission (IEC), and International Telecommunication Union Telecommunication Standardization Sector ITU-T, originally defined in 1984 as part of CCITT X.409:1984.